UPDATE: A DoD press release states that "Nearly all of the debris will burn up on reentry within 24-48 hours and the remaining debris should re-enter within 40 days." They also say that confirmation that the fuel tank carrying the hydrazine was disrupted will come within 24 hours. Stay Tuned.

UPDATE II: CNN video of a press conference by the Pentagon has some footage of the missile very clearly hitting the satellite. Very cool… and at the very end of the few seconds of the footage, I’d swear a bow wave forms as the expanding cloud slams into the very thin atmosphere at that height. Also, they appear to have seen indications of hydrazine in a spectrum of the explosion they took, which means it looks like they hit the tank.

At approximately 10:26 p.m. EST today, a U.S. Navy AEGIS warship, the USS Lake Erie, fired a single modified tactical Standard Missile-3, hitting the satellite approximately 247 kilometers (133 nautical miles) over the Pacific Ocean as it traveled in space at more than 17,000 mph.

Well then. This was reported to have been postponed, but I guess the seas calmed down enough for them to take the shot.

Interestingly, the CNN story says the missile had no warhead. A simple impact is enough to do the deed; at relative velocities of several miles per second a small pebble can do serious damage.

I’ll note that in their video, CNN shows Hubble when talking about the satellite. Geez.

I don’t know what more there will be to this story until the pieces come down, which may take a few more weeks. As usual, when I learn more, I’ll post!

No news report had yet reported on the details of the expected result of the impact, other than the inaccurate “blowing it up.” Presumably the major intended effect was to rupture the hydrazine tank.

Neither did they mention the expected speed of collision, which could be anywhere from 0 to 34,000 mph (matching velocity versus headon collision).

But if it was a significant velocity, wouldn’t the impact slow the satellite (or the center of mass of the remaining pieces of the satellite) and precipitate reentry even sooner? Will it really take several weeks for reentry since the original reports were claiming an unassisted reentry of early March?

Can an impact as high as this be used to slow the spacecraft enough to increase the predictability of the reentry swath?

From Prince George, British Columbia we were treated to a great show – as our crowd at the Observatory were just getting the first healthy glimpse of the eclipsed moon the sky above broke out into six near-bolide streaks across the sky (Auriga –> Ursa Maj) with tails lasting up to a minute. Satellite, we presume? They were wonderful, accompanied by a crowd of “ooooh’s” in the background! It stole the show from the moon…

What Timothy said.. simple physics. I think the impact will have a significant effect on the speed of the satellite. Seeing the the navy is going for a “kinetic” kill, just take the mass of the projectile and do some math or something. I’m sure they cooked up lots of models of debri fields

Ever considered that a decent optical recce satellite is “just” a telescope (Hubble) pointed in the “wrong” direction” (more or less give some details about relative speeds of satellite and target and angles of view and such)

Obviously this is a government cover story to disguise the fact that that asteroid made a U-turn and came back to get us when we weren’t looking because it’s piloted by Aliens from Zeti Rediculus. Or they might have been on bicycles.

Either way, they had to shoot it down with their frickin’ shark lasers.

Also, Oprah is one of them, (you can tell because she weighs the same as a duck) and she told me not to tell anyone (by telepathy, of course) or else she would aaaaarrrrrrggghhh…

“Debris will begin to re-enter the Earth’s atmosphere immediately,” the department said. “Nearly all of the debris will burn up on re-entry within 24-48 hours and the remaining debris should re-enter within 40 days.”

Impact energies are interesting in those sort of collisions. For the most part, the impactor should punch strait through, it’s not easy to get them to fragment reliably at those speeds.
Heh, an explosive warhead wouldn’t be finished exploding by the time it passed through at those speeds.

They’ll be relying on fragmentation off wherever it enters that’ll punch through the rest of the body at a slightly wider angle. Can’t say it’d reliably disintegrate the structure, but it’d leave a bigger mess in the back than the front, and you could get reasonable disintegration depending on the internal structure (there needs to be much more internal shrapnel created by the initial spread, effectively using up more of the energy on it’s quick trip through).

The thing would burn up in the atmosphere either way. It’s not shielded, and a full fuel tank would have *much* more momentum to (literally) burn off than an empty one.

It’s still a good test of a an anti-sat weapon, assuming their “success” is somewhat more literal than the old patriot test results turned out to be.

Yesterday on (I think) Reuters’ web site that the combined speed was about 22,000 mph.

As for showing an image of the Hubble… wasn’t one of the Keyholes (KH-11) thought to have resembled Hubble? I had heard talk back when Hubble was launched that it was somewhat based on one of these spy sats.

“Interestingly, the CNN story says the missile had no warhead. A simple impact is enough to do the deed; at relative velocities of several miles per second a small pebble can do serious damage.”

BA, you sound as if you’re surprised by this fact. Others have chided you in earlier posts on your use of the phrase “blow up” when referring to this shot. Yet you used it again in this article? What’s up with that?

I’ve got mixed feelings about this & don’t really know whether to congratulate the folks involved for achieving an impressive technological feat with such good execution and accuracy? Or condemn them for the further militarisation of space and the negative implications this has – diplomatically and for space usage & exploration generally?

Aren’t there some serious issues here with the international (UN?) law on space -in terms if not militarizing space or using it for aggressive military purposes?

Now ok, it was rationalised – not overly convincingly – as a possible threat to people with hydrazine fuel but c’mon, there’s a lot of understandable cynicism about that!

Wasn’t there a lot of hydrazine or suchlike dangerous chemicals spilt when ‘Columbia’ broke up on re-entry? Seem to recall NASA using that as a warning-off from morbid ghouls picking up pieces of the shuttle debris and seling them on e-bay or whatever ..

The real reasons being showing off to China and preventing it falling into non-US military hands strikes me as being much more credible. & just because China does something bad doesn’t mean the USA has to copy them .. “Great Powers” politics is so stupidly & dangerously childish on occassion.

(I blow up a satelite! Hah Hah! Hey! I can blow one up too! Ner,ner! Grow up please “Uncle Sam” and “Chinese Lil’ Emperors”!

In fairness, I ‘spose all three reasons could be combined to justify destroying Sat. USA-193 but … hmmn… as I said, mixed feelings & mixed messages there.

I am glad of one thing though – at least unlike in ‘Futurama’ they didn’t miss the real target and blow up Hubble by mistake!

“Aren’t there some serious issues here with the international (UN?) law on space -in terms if not militarizing space or using it for aggressive military purposes? ”

Should be :

Aren’t there some serious issues here with the international (UN?) law on space – in terms *of* not militarizing space or using it for aggressive military purposes?

Obviously!
—————
‘Needless to say’,
It need not be said
But so many needlessly say it.
Is this because its not ‘needless to say‘
And that’s why we so often say it?
For if its not needless
Then needs must we say
But if not we needn’t e’er say it!

I thought this sort of thing was hard to do and they weren’t having much luck developing antiballistic missiles to intercept ICBMs. Are the computers and tracking better, or are satellites just easy to hit?

Satellites are easier to hit. You know the path well ahead of time, and there’s plenty of time to prepare. ICBM’s give little notice and you have to observe them to project where they will be when you want to hit them.

StevoR said:
> Now ok, it was rationalised – not overly convincingly – as a possible threat to people with hydrazine fuel but c’mon, there’s a lot of understandable cynicism about that!

> Wasn’t there a lot of hydrazine or suchlike dangerous chemicals spilt when ‘Columbia’ broke up on re-entry? Seem to recall NASA using that as a warning-off from morbid ghouls picking up pieces of the shuttle debris and seling them on e-bay or whatever ..

Yes, there was some hydrazine on Columbia, and there was concern over contaminated parts. Not sure, but it sounds like you’re trying to belittle the hydrazine risk by saying Columbia had hydrazine, too. Couple differences. 1) Columbia had used up most of the hydrazine on board, vs this satellite having full tank. 2) Columbia broke up, dispersing most of the remaining hydrazine, while the satellite was predicted to have tanks survive reentry intact and thus have a large amount concentrated in the strike zone. Also, and this is significant, Columbia was intended to return intact, so breaking up and spilling hydrazine was not intentional, nor was scattering potentially contaminated parts across Texas.

The hydrazine was a red herring. Virtually every spacecraft and rocket ever launched carries some form of it in some amount. A ton seems like a lot, but is it really? The Apollo lunar module had 10+ tonnes of the hypergolic fuels hydrazine (actually Aerozine-50) and nitrogen tetroxide. The Delta II second stage, based on the LM ascent engine, carries about 6 tonnes of the same propellants. The real hypergolic guzzlers were the Titans (a Titan-IVB launched Cassini): 155 tonnes for the first stage and 35 tonnes for the second stage.

These are serious amounts of nasty chemicals for those who work with or near them. Sometimes these rockets do blow up shortly after launch and create a hazard. But the USA-193 tank simply wasn’t a credible threat to anyone on the ground. Spacecraft fuel tanks are thin to save weight, and break apart quickly on re-entry. Hydrazine is flammable (it is a rocket fuel after all) so at most it would have briefly brightened the USA-193 re-entry fireball. BFD.

A comment about “kinetic kill” satellite weapons. At these velocities relatively little momentum is exchanged. It’s as if each object independently explodes and their debris clouds pass through each other with their centers of mass moving more or less unchanged.